Another contractor which provided interrogators to the US military, CACI, is expected to go on court trial over similar allegations.

The US government is immune from lawsuits stemming from combat actions by the military in time of war, but courts are still establishing whether independent firms operating in war zones should have the same legal immunity.

Abu Ghraib came to world attention after the release in 2004 of photographs showing the physical, sexual harassment and psychological abuse of Iraqi prisoners by US guards.

The images showed prisoners facing dogs, being stripped naked and wired up as if being subjected to electric shocks and became a turning point of the Iraq war.

Eleven soldiers were convicted of breaking military laws, but many received sentences of a just a few years. The last remaining soldier in prison convicted in the case was released in August 2011.(IY)